1. Field of the Invention
This invention relates to an oil-absorbent polymer and uses found therefor. More specifically, relates to a swelling absorbent for oil which swells by efficiently absorbent oil and exhibits a markedly improved oil-absorbent capacity at low temperatures, uses found therefor such as, for example, substrate for gradual release of aquatic chemical agents, gelled aromatic composition, gelled insectifugal, insecticidal, and fungicidal compositions, aquatic antifouling composition, fish-luring composition, solid fuel composition, oil absorbent material, oil mist filter, oil sealing material, paper excellent in printability, thermosensitive recording material, and pressure sensitive recording sheet, a method for the production of an oil-absorbent material, and a method for the removal of oil dissolved in water.
2. Description of the Prior Art
In recent years, the recovery of oil from the sea contaminated by accidentally effused oil and from the oil-containing waste water has come to constitute itself a serious problem in terms of environmental control. The desirability of the debut of a method for convenient disposal of spent oils discarded in small amounts from homes and plants and machine oils and other oils leaking from plants has been finding earnest recognition.
As one of the dominant means for the recovery of accidentally effused oil or oil entrained by waste water or for the disposal of spent oil or leaking oil, the procedure which comprises causing an absorbent for oil to absorb the unwanted oil and then subjecting the oil-impregnated absorbent to incineration or some other similar after-treatment has been heretofore adoped. The commercially available absorbents for oil which are effectively usable in this procedure include natural plant type oil absorbents such as rice hulls, straw, pulp, peat, and cotton; inorganic type oil absorbents produced by subjecting inorganic porous powders of lime, silica, and pearlite to a treatment for impartation of water repellency; synthetic fiber type oil absorbents using polypropylene fibers, polystyrene fibers, and polyurethane fibers; and foam resin type oil absorbents using polyurethane foam, for example.
Most of these conventional oil absorbents, however, fail to offer a fully satisfactory capacity for oil absorption. Further, because of their oil-absorbing mechanism which resides in causing a given oil to be absorbed and retained fast in the voids or pores distributed in their textures, these conventional oil absorbents suffer from the following disadvantages: (1) They produce virtually no voluminal change from the absorbed oil and gain so greatly in bulk density as to inconvenience the works of storage and handling. (2) They are deficient in ability to retain the absorbed oil. Particularly the natural plant type, synthetic fiber type, and foam resin type oil absorbents readily release the absorbed oil even under only slight external pressure. As a result, they call for highly complicated aftertreatments. (3) Though they generally have undergone a treatment for impartation of water repellency, they suffer from a decline of their oil-absorbing ability because of the infiltration of water in the voids after their protracted use in an oil-water mixture system. (4) Though they are capable of absorbing oil from the suspension of oil in water to a certain extent, they are incapable of substantially absorbing oil from the water containing dissolved oil.
As a means for the solution of these problems, oil absorbents of the type using synthetic resins as polymers adapted to absorb a given oil and swell with the absorbed oil have been reported in several articles of literature. The copolymer of t-butyl styrene/divinyl benzene [JP-A-45-27,081(1970)], the cross-linked polymer of t-butyl methacrylate and/or neopentyl methacrylate [JP-A-50-15,882(1975)], the cross-linked polymer of menthyl methacrylate [JP-A-50-59,486(1975)], and the polynorbornene rubber [represented by the product of CdF Corp. marketed under trademark designation of "Norsolex AP"] are examples of the oil absorbent of this type.
The cross-linked polymer of t-butyl methacrylate and/or neopentyl methacrylate, however, fails to exhibit a fully satisfactory absorbing capacity for aliphatic hydrocarbon type oils, though it possesses an appreciable absorbing capacity for such aromatic hydrocarbon type low boiling oils as benzene. The copolymer of t-butyl styrene/divinyl benzene, the cross-linked polymer of menthyl methacrylate, and the polynorbornene rubber manifest an appreciable absorbing capacity for aromatic and aliphatic low boiling hydrocarbon type oils but an inferior absorbing capacity for fatty acid ester type oils, fatty acids, higher alcohols and other similar polar oils, and highly viscous oils. These synthetic resin type oil absorbents, therefore, find utility only in applications of their own limits. They are particularly unfit for the disposal of used edible oils. Moreover, these oil absorbents are slow in absorbing an oil. Particularly at low temperatures, most of these oil absorbents exhibit either a very low oil-absorbing capacity or virtually no oil-absorbing capacity. Thus, they have the disadvantage that they manifest their effects only with difficulty when they are used in a cold district.
Heretofore, in the fields of agricuture, forestry, fishery, and water treatment which have something to do with water, various underwater dissolvable chemical agents have been used for the purpose of extirpating insects, fungi, and weeds in farmlands, rustproofing metals, purifying solutions, defoaming liquids, protecting marine farms from algae, promoting growth of organisms, and luring fish in the sea. These chemical agents have been used by being thrown or scattered in a body of water under treatment either in their unmodified form or in the form of a solution or a dispersant. This method of use, however, has the disadvantage that the chemical agent manifests only a transient effect and overflows the body of water under treatment to be wasted and suffered to contaminate the environment and adversely affect human bodies. In recent years, therefore, the desirability of developing a technique for gradual release of a chemical agent has been finding growing recognition.
As such techniques for gradual release of a chemical agent, several methods which generally comprise depositing a chemical agent on a substrate and allowing the deposited chemical agent to be gradually released from the substrate under water have been reported; e.g. (1) methods which comprise preparing a solid substance having a chemical agent contained in a substrate of an inorganic substance or a polymeric compound and placing this solid substance in a given body of water thereby allowing the chemical agent to be gradually released from the substrate into the water and (2) methods which comprise preparing a coating material having a chemical agent incorporated in a substrate of a non-crosslinking film-forming macromolecular compound, applying this coating material to a given structure, and immersing the coated structure in a body of water thereby allowing the chemical agent to be gradually released from the applied coating.
In the group (1) are included a method which uses clay or a mineral substance as a substrate and causes a chemical agent to be contained in this substrate, a method which uses cement or calcined plaster as a substrate and impregnates this substrate with a chemical agent [JP-A-53-138,885(1978)], and a method which causes a chemical agent to be contained in an aqueous gel [JP-A-57-163,302(1982)], for example. These methods, however, have the disadvantage that the solid product is liable to disintegrate or dissolve, deficient in ability to retain the chemical agent, susceptible to the influence of water temperature or water current and, therefore, deficient in ability to control the speed of release of the chemical agent, and incapable of easily retaining the effect of the chemical agent for a long time.
In the group (2) are included methods which use non-crosslinking copolymers of (meth)acrylic esters as coating macromolecular compounds [JP-A-51-7,034(1976) and JP-A-58-120,678(1983) and JP-B-1-54,388(1989)], for example. These methods, however, have the disadvantage that since the polymeric compounds used therein are deficient in ability to retain a chemical agent in spite of their possession of a film-forming property, they do not easily allow preparation of a coating material capable of retaining the film-forming property and, at the same time, containing a chemical agent in a large amount and further that since the compounds maintain no sufficient control over the speed of release of the chemical agent, they do not allow the produced coating material to manifest the efficacy of the chemical agent continuously for a long time.
In consequence of changes in the residential environment and improvements in comfortableness of the living spaces, consumers taking a serious interest in the scent have been on the increase and aromatic agents have been establishing themselves as daily necessities in recent years. These aromatic agents have been heretofore used mainly in water closets. At present, they are finding growing utility additionally in room interiors and car interiors. They are expected to find utility in increasingly numerous fields.
The aromatic agents come in various types such as the spray type, liquid type, solid type, and gel type. The aromatic compositions of the gel type, among other types, find particularly popular acceptance because they excel in ability to effect gradual release of the aromatic scent and have no possibility of entailing liquid leakage even when they topple.
The aromatic compositions of the gel type are generally classified under the aqueous gel type and the oily gel type. The aromatic compositions of the aqueous gel type are produced by gelling water with such gelling agents as agar, carrageenan [JP-A-54-135,229(1979)], and a water-soluble polymeric compound [JP-A-55-81,655(1980)] thereby preparing aqueous gels and causing an aromatic essence to be dispersed or solubilized in the aqueous gels in the presence of a surfactant.
These aromatic agents of the aqueous gel type, however, have only a limited aromatic essence content because the aromatic essences are insoluble in water. Since they are generally used as containing an aromatic essence only in a concentration on the order of several percent, they are poor in intensity of aroma and are deficient in ability to retain aroma. They further have the disadvantage that the speed of diffusion of aroma is varied by humidity and the water in the gel is separated and frozen at low temperatures and the gel possesses low strength and yields to dissolution at high temperatures.
In contrast, the aromatic agents of the oily gel type are produced by gelling an aromatic essence or a mixture of an aromatic essence with an oily diluent by using such gelling agents as sodium stearate [JP-A-55-141,243(1980)], benzylidene sorbitol [JP-A-59-77,859(1984)], an amino acid type gelling agent [JP-A-61-206,450(1986)], a styrene-butadiene-styrene copolymer [JP-A-62-249,652(1987)], and a styrene-ethylene-butylene-styrene copolymer [JP-A-62-249,653(1987)], for example. Most of them embody improvements which are capable of eliminating the drawbacks of the aromatic agents of the aqueous gel type.
When sodium stearate, an amino acid type gelling agent, a styrene-butadiene-styrene copolymer, or a styrene-ethylene-butylene-styrene copolymer is used as a gelling agent, the dissolution of the gelling agent in the aromatic essence necessitates a high temperature and consequently tends to entail diffusion, degeneration, discoloration, etc. of the aromatic essence. Further, the oily gel has the disadvantage that the gel which is formed elaborately is re-dissolved once it is exposed to a high temperature as in the car interior.
A procedure which comprises cross-linking an acetoacetylated oligomer in an aromatic essence thereby producing an aromatic gel has been disclosed in [JP-A-62-19,171(1987)]. Specifically, this procedure comprises in cross-linking and gelling acetoacetylated 1,4-polybutadiene in the aromatic essence at normal room temperature in the presence of a cross-linking agent. Most aromatic essences generally possess a reactive substitutent. When such an aromatic essence is used, there ensues the disadvantage that the reaction between the acetoacetyl group and the aromatic essence proceeds to the extent of precluding the formation of the gel. The procedure under present discussion, therefore, requires to use only a specific aromatic essence and dilute this aromatic essence with a large amount of an oily diluent and, therefore, finds utility only in a narrow range of applications. Moreover, the aromatic agent using this acetoacetylated oligomer suffers from the disadvantage that the aromatic essence emits the aroma feebly and tends to lose the constant level of scent.
The gel produced by using the aforementioned conventional oily gelling agent betrays poor strength. For the produced gel to acquire ample strength, therefore, the amount of the gelling agent to be used must be remarkably increased. More often than not, the gel using the gelling agent has the disadvantage that it contains the residue of the gelling agent in a large amount and acquires an opacified texture. Further, the aromatic agents of the conventional oily gel type have the disadvantage that the aromatic essence contained therein in a high concentration is refractory to an attempt to gradually releasing the aroma at a constant level of scent over a long period of time and, actually, the aromatic essence is diffused very quickly or only a specific component of the aromatic essence is diffused in the early stage of use to bring about early impairment of the constant level of scent.
In recent years, in the field of insectifuges for use with clothing, such subliming solid agents as P-dichlorobenzene, naphthalene, and camphor which have heretofore found popular acceptance are now discouraging consumers from continuing their use on account of smell and toxicity. Volatile liquid insectifuges which emit no (or scanty) odor and operate with high safety (such as, for example, the synthetic pyrethroid type insectifuge) have come to attract attention instead. This trend has been giving rise to a demand for a technique capable of providing stable and lasting gradual release of a volatile chemical agent. In the field of such agricultural pesticides as insecticides and fungicides, generally those of the liquid spray type have been heretofore used. In recent years, since these pesticides manifest their effects only transiently, a demand for a technique which allows gradual release of these pesticides and enables the effects of the pesticides to be manifested continuously for a long time has come to take shape in this field.
Several techniques for gradual release of such chemical agents have been reported to the art, including the method which gels a given chemical agent by the use of a gelling agent and the method which causes a chemical agent to be incorporated in a polymeric matrix, for example.
The products obtained in accordance with the method which gels a chemical agent by the use of a gelling agent include an aqueous gel using locust bean gum and xanthane gum as gelling agents [JP-A-53-50,346(1978)], a gel type insecticide using an N-acylamino acid derivative as a gelling agent [JP-A-63-222,104(1988)], and a gel-like solid agent endowed with enhanced viscosity by the use of finely divided silica and alcohol [JP-A-54-92,630(1979)], for example.
These methods which rely on use of a gelling agent invariably have drawbacks. The aqueous gel has the disadvantage that since the speed of diffusion of the chemical agent used therein is affected to a large extent by changes in temperature and humidity, the effect of the chemical agent cannot be stably maintained for a long time, the water in the gel tends to be frozen or separated, and the gelling treatment cannot be effectively applied to a chemical agent which is susceptible of hydrolysis.
When an N-acylamino acid derivative is used as a gelling agent, it requires to be mixed with a volatile chemical agent and preparatorily dissolved at a high temperature. Thus, the method using thie gelling agent cannot be applied to a chemical agent of low boiling point or a chemical agent ready to degenerate with heat and the produced gel has very low strength.
The gel-like solid agent using finely divided silica acquires its enhanced viscosity owing to the thixotropic effect of the finely divided silica. It, therefore, has the disadvantage that it is deficient in stability of the gel and liable to entail separation and disintegration while in storage or in use.
The products reported to the art as obtained in accordance with the method which comprises having a chemical agent incorporated in a polymeric matrix include a mildewcide having a gasifiable chemical agent dispersed in an ethylene-vinyl acetate copolymer [JP-A-56-26,811(1981)] and an insecticidal composition obtained by mixing an insecticide with a copolymer of styrene or .alpha.-methylstyrene and an unsaturated carboxylic anhydride and cross-linking the resultant solution by the use of a cross-linking agent [JP-A-57-80,302(1982)], for example. Though the product using the ethylene-vinyl acetate copolymer indeed manifests its effect as a carrier for a gasifying solid chemical agent, it nevertheless has the disadvantage of being inapplicable to a liquid chemical agent.
The method which comprises cross-linking the copolymer of styrene or .alpha.-methylstyrene and the unsaturated carboxylic anhydride has the disadvantage that it is applicable only to limited chemical agents and inapplicable to any chemical agent containing in the molecular unit thereof a substituent reactive with the carboxylic anhydride or the cross-linking agent because this method requires to mix the copolymer with the chemical agent preparatorily and solidify the resultant solution with the cross-linking agent.
The conventional method which comprises causing a chemical agent to be incorporated in a polymeric matrix has the disadvantage that the product exhibits a poor ability to retain the effect of the chemical agent for a long time, produces the residue in a very large amount at the end of its service, and encounters difficulty in displaying the extent of consumption of the effect of the chemical agent because this method is incapable of effecting the incorporation of the chemical agent in an ample amount.
Further, most of the conventional techniques described above have the disadvantage that the products thereof exhibit a poor ability to control the diffusion of the chemical agent, suffer the chemical agent to diffuse abruptly in a large amount in the initial stage of service, and fail to manifest the effect of the chemical agent amply for a long time.
Heretofore, in the field of fishing and angling alike, the practice of scattering ground bait within a fixed area for the purpose of attracting fish and enhancing the efficiency of catch has been followed. As baits, such natural creatures as angleworms, lugworms, krills, and shellfish have been generally used either in their unmodified form or in a form kneaded with bean-curd refuse or bread crumb.
These natural baits have the disadvantage that they have no stable supply, encounter difficulty in allowing protracted conservation, necessitate cold storage for prevention of putrefaction, and inconvenience transportation because of bulkiness.
In recent years, the feasibility of a technique for producing a bait capable of gradual release of a fish-luring substance and enhancing the efficiency of catch has been under study. So far, fish-luring agents and false baits having a fish-attracting substance incorporated in an inorganic or polymeric compound have been reported to the art.
To be specific, a fish-luring agent produced by impregnating cement or calcined gypsum with a fish-attracting substance such as fish oil [JP-A-53-138,885(1978)], a false bait grade aqueous gel composition comprising of a polysaccharide and a polyvalent metallic compound [JP-A-62-190,037(1987)], and false bait grade organic polymer compositions allowing a fish-attracting component to be dissolved out simultaneously with a water-soluble organic polymer from a water-insoluble organic polymer [JP-A-59-74,937(1984), JP-A-59-98,637(1984), and JP-A-60-153,738(1985)], have been reported, for example.
These conventional products, however, have the disadvantage that they provide lasting manifestation of a fish-attracting effect at a constant level only with difficulty and necessitate early replenishment or replacement with new supply because they exhibit a poor ability to retain such fish-attracting oils as fish oil, animal oil, vegetable oil, and insect oil and betray their inability to effect full control of the speed of release of such oils.
Such underwater objects as bottom parts of ships, underwater structures, and fish nets are susceptible to attachment of such aquatic organisms as barnacles, polyzoans, and sea lettuces and, as a result, the ships incur loss of cruising speed, the underwater structures succumb to corrosion, and the fish nets suffer from clogging of their meshes and entail mass destruction of fish enclosed therein. To preclude these disadvantages, antifouling agents have been used as scattered in bodies of water under treatment or applied to the bottom parts of the ships or to the fish nets. The conventional antifouling agents, however, have the problems of poor economy and exertion of adverse effects on the environment inclusive of human bodies because they produce an effective antifouling action only for a short time and, therefore, necessitate frequent repetition of scattering or application and their excesses flow out of the bodies of water under treatment immediately after the scattering or application. In the circumstances, the necessity for developing a technique for enabling an antifouling agent to manifest a lasting effect for a long time has come to find mounting recognition.
Methods which produce antifouling agents endowed with an improved effect-retaining property by the use of rosins and non-crosslinked copolymers of (meth)acrylic esters as vehicles therefor [JP-A-51-7,034(1976), JP-A-58-120,678(1983), and JP-B-1-54,388(1989)], for example, have been known to the art. Since the vehicles used for these antifouling agents, however, have only a poor ability to retain an antifouling component in spite of the possession of a film-forming property, they are susceptible to the influences of the temperature and current of water and incapable of fully controlling the speed of release of the antifouling component. Further, these vehicles have a disadvantage that they are not easily enabled to incorporate therein a large amount of an antifouling agent while retaining the film-forming property and they are not capable of retaining the effect of the antifouling agent for a long time.
Solid fuels have been heretofore used for camping and tabletop cooking. Most of them are products obtained by using such a low boiling alcohol as methanol or alcohol as a fuel component and gelling the fuel component by the use of a metallic soap or a sorbitol type gelling agent and, therefore, have the following drawbacks.
(1) These fuels have a small calorific value and are incapable of producing an intense fire stably for a long time.
(2) The possibility that, by the heat of the combustion, the components for combustion of these fuels will be partly consumed in the combustion and partly diffused into the ambient air as accompanied by leakage of such harmful substances as methanol and aldehyde and the fuels, on exposure to an elevated temperature while in storage, will induce ignition is high.
(3) The gels incorporating the combustion components are fluidified and eventually liquefied at an elevated temperature.
In recent years, the recovery of the oil accidentally effused on the sea or the oil entrained by the waste water has come to pose a serious problem to the environmental conservation. A strong desire has been expressed for the development of a method for convenient disposal of waste oil discarded in a small amount from homes and plants and machine oil and other similar oils leaking from plants.
As one efficient means for recovering the effused oil or the oil entrained by the waste water or for disposing of the waste oil or leaking oil, the method which comprises causing an absorbent to absorb the oil and subjecting the impregnated absorbent to an aftertreatment of incineration has been in use to date. The absorbents used heretofore for this method include synthetic resin type absorbents formed of such hydrophobic fibers as polypropylene fibers, polystyrene fibers, and polyethylene fibers or non-woven fabrics of such hydrophobic fibers.
Since the conventional synthetic resin type absorbents effect the absorption of oil by causing the voids distributed therein to absorb and retain the oil fast therein, they have the following disadvantages.
(1) They are deficient in ability to retain the absorbed oil, substantially destitute of ability to retain any oil of low viscosity, and ready to release the absorbed viscous oil even under very slight pressure and liable to let down the viscous oil, rendering very difficult the aftertreatment of the impregnated absorbents.
(2) When they are used for the recovery of the oil contained in the oil-water mixture or the oil floating in the form of a thin film on the surface of water, since they absorb the oil only in a low ratio and absorb a large amount of water as well, they sink under water and render their recovery difficult and, after recovery, they are incinerated with great difficulty.
(3) Since the absorbents produce virtually no voluminal change from the absorbed oil, they have high bulkiness before absorbing oil. Thus, they inconvenience the work of storage and handling.
The ventilating fans in kitchens and the ventillating devices in plants are prone to adhesion thereto of oil mist drifted in the air. They, therefore, entail the disadvantage that they tend to grow sticky and collect dirt rather quickly, incur serious impairment of appearance, suffer loss of hygiene, and sacrifice operational efficiency.
At such places as painting plants which inevitably emit oil mist, persons seeking a measure to prevent degradation of labor environment have expressed a strong desire for the development of a method which is capable of providing convenient removal of the oil mist.
For the removal of the oil mist in these circumstances, the method which comprises setting a filter capable of absorbing oil as opposed to the front surface of a ventillating device or an air circulating device has been heretofore employed. Particularly in recent years, for the purpose of obviating the necessity for cleaning this filter, the method which comprises using the non-woven fabric of such sysnthetic resin as polypropylene or polyester as a disposable filter has come to find growing utility.
These conventional filters, however, are deficient in ability to absorb oil mist or incapable of absorbing a large amount of oil mist and, therefore, have the disadvantage that their surfaces collect trickles formed of absorbed oil mist and grow sticky with absorbed oil mist and soil a user's hands when the user changes the used filter with a new supply. Further, since the absorbed oil forms a film on the filter and induces clogging of the filter and seriously degrades the ventilating fan's operational efficiency, these conventional filters incur the disadvantage that they must be frequently replaced.
As a means for sealing joints in an oil pipeline or parts of such machines as pumps which are exposed to oil, the method which comprises improving the oil tightness of such joints by using a sealing material made of an oil-swelling elastomer has been known to the art. An example of the sealing material is produced by kneading such an oil-swelling substance as natural rubber with an oil-resistant synthetic rubber.
The conventional sealing materials, however, require to incorporate therein a fairly large amount of the oil-swelling substance for the purpose of enabling the entire elastomer to be suitably swelled. Thus, they have the disadvantage that the elastomer, after absorbing the oil, suffers the shape-retaining property thereof to be markedly degraded. Most of these conventional sealing materials have the problem of suffering from slow absorption of oil and requiring a long time before manifesting the effect of precluding oil leakage.
In recent years, in consequence of a vigorous growth in the demand for color prints such as gravures and calendars as well as for letterpress prints such as newspapers, magazines, and various publications, the desirability of developing a technique for producing prints at a high speed with high accuracy has been finding enthusiastic recognition.
As a promising means for improving the printability of paper, the concept of enhancing the receptivitity of the paper for ink specifically by enabling the solvent component of the ink to be quickly absorbed in the paper has been proposed.
As a means for enhancing the absorption of the solvent component of the ink by the paper, the method which comprises causing the paper or the applied coating layer on a coated paper to incorporate therein porous inorganic particles possessing an ability to absorb the solvent has been known to the art. In the case of the coated paper, the method which comprises adjusting the interstices between pigment particles in the applied coating layer to a suitable size and allowing the solvent component of the ink to be absorbed in the resultant capillaries has been popularly in practice.
Although these conventional techniques, however, have advantages that the pigment component of the ink allows relatively easily to remain on the surface by adjusting the diameter of pores because the solvent component of the ink is absorbed in the pores, there is disadvantage that it is difficult that only solvent component allows to absorb under remaining a binder polymer and pigment dissolved in the solvent and fixness of the ink lacks.
The thermosensitive recording material is a product to be obtained by forming on a substrate such as paper or film a thermosensitive coloring layer which produces a color on exposure to heat. It has heretofore found utility in printer papers, facsimile papers, passenger tickets issued from automatic vending machines, etc.
The thermosensitive recording material, however, has the disadvantage that, in the course of the application of heat at the time of recording, part of the molten substance occurring in the thermosensitive coloring layer adheres to the thermal head and consequently gives rise to a ropy deposit and impairs the regularity of paper feeding and the ropy deposit on the thermal head solidifies and consequently smears dots and obscures the recording. Further, the thermosensitive recording material offers only poor resistance to oils and solvents. It, therefore, has the disadvantage that when the record produced thereby touches oil such as the grease from the human skin or the hair cream or solvent such as contained in the adhesive tape or the adhesive agent, the colored part of the record fades or vanishes and the white part thereof produces a color, with the result that the recorded image is obscured.
As a means for solving this disadvantage, the method which comprises causing the thermosensitive coloring layer to incorporate therein a filler such as calcium carbonate, aluminum hydroxide, silica, or clay thereby preventing the molten substance in the thermosensitive coloring layer from adhering to the thermal head has been heretofore used. The effect of this method, however, does not deserve to be called fully satisfactory.
The method which, for the purpose of improving the resistance to oil, comprises causing a metal salt of a P-alkylbenzonic acid or a metal salt of an O-benzoylbenzonic acid to be incorporated in a photosensitive coloring layer containing a basic colorless dye and a monophenolic 4-hydroxyphenyl compound [JP-B-2-26,874(1990)] has been reported to the art. This method, however, manifests its effect only in the case of a specific developer and sparingly manifests its effect in the case of a combination with other developer possessing a high developing effect.
The pressure-sensitive recording sheets which are used as for copying slips in business offices each comprises an upper sheet having formed on the lower surface of a substrate such as of paper a layer including microcapsules containing an involatile oily solution of a color-producing dye such as a leuco dye and a lower sheet having formed on the upper surface of a substrate a layer containing a developing agent capable of reacting with the color-producing dye and causing the color-producing dye to produce a color. They are stacked with their upper sheets superposed severally on their lower sheets in such a manner that the microcapsule-containing layer and the developer-containing layer are opposed to each other. The pressure of a stylus exerted downwardly on the upper surface of the upper sheet fractures the microcapsules and establishes contact between the color-producing dye and the developing agent and consequently forms a given recorded image on the lower sheet.
The pressure-sensitive recording sheets enjoy the advantage that the color-producing dye quickly permeates the developer-containing layer (hereinafter referred to occasionally as a "developer layer") and quickly effects the production of color because this color-producing dye is in the form of a solution in an involatile oily solvent. They, however, have the disadvantage that the color-producing dye blurs the recorded image and prevents its from acquiring a beautiful finish. They also suffer from the disadvantage that the recording image is blurred or vanished when it is suffered to touch oil such as the grease from the human skin or the hair cream or solvent as contained in the adhesive tape or the adhesive agent.
In recent years, the necessity for a technique capable of purifying waste water to a high degree for the sake of conservation of the environment and reclamation of the plant effluent or the household sewage has come to find mounting recognition. Also in ease where a river or a lake, in consequence of contamination, is utilized as a source of water and purified to produce tap water such as city water, this technique for thorough purification of contaminated water is yearned for.
The impurities which are contained in the waste water or the contaminated water mainly include organic compounds, water-soluble inorganic compounds, solid particles, and various fungi, for example. Among other impurities cited above, the oily impurities exert adverse effects on the environment inclusive of human bodies and induce various problems due to offensive odor, displeasing taste, foaming, and coloration even when they are dissolved only slightly in water. Particularly recently, the removal of halogen compounds extremely harmful to human bodies from a water having them dissolved therein has come to pose an important task to the conservation of the environment.
As a means for removing such oily impurities dissolved in water, the method which comprises mixing the waste water or the contaminated water resulting from a primary treatment with granular activated carbon thereby subjecting the dissolved oily impurities to a treatment of adsorption and purifying the water to a high degree has been adopted to date.
The activated carbon, however, exhibits the ability of adsorption not only to the oily impurities desired to be removed but also to such other impurities than the oily impurities as highly water-soluble substances and sparingly water-soluble colloidal particles. In the waste water or the contaminated water containing these impurities, the activated carbon's effect in removing the oily impurities does not last long because the sites of adsorption and the pores in the activated carbon are quick to be clogged with the impurities other than the oily impurities. Further, the activated carbon has no fully satisfactory ability to adsorb the oily impurities and, therefore, suffers from the disadvantage that it is incapable of providing thorough removal of oily impurities from the waste water or the contaminated water containing the oily impurities in a high concentration. Moreover, the granular activated carbon effects the adsorption at a low speed and, therefore, requires an amply long contact time with the waste water or the contaminated water. When it is used for the removal of oily impurities as packed in a column, for example, it has the problem of very poor efficiency of treatment because the speed of passage of the water under treatment through the column cannot be increased.
An object of this invention is to provide an oil-absorbent polymer and uses therefor.
Another object of this invention is to provide a swelling absorbent for oil, which absorbs any of a wide range of oils including edible oils and fatty esters at a high speed with a great capacity and retains the absorbed oil with ample fastness and, moreover, manifests this oil-absorbing ability fully even at low temperatures.
Still another object of this invention is to provide a substrate for underwater gradual release of a chemical agent such as insecticide, fungicide, herbicide, rustproofing agent, purifying agent, deforming agent, algicide, growth accelerator for organisms, and fish-luring agent, which substrate allows the chemical agent to dissolve out into water at a fixed speed and consequently enables it to manifest its effect for a long time.
Yet another object of this invention is to provide an oily gel aromatic agent composition which permits the production thereof to proceed satisfactorily at normal room temperature, excels in the ability to control the diffusion of an aromatic essence without reference to the kind of aromatic essence and the ability to retain the shape of the gel, contains the aromatic component in a high concentration, produces a residue only in a small amount at the end of service, and exhibits highly satisfactory transparency.
A further object of this invention is to provide a gel-like insectifugal, insecticidal, or fungicidal composition which exhibits a high shape-retaining property even at normal room temperature, contains a volatile insectifugal, insecticidal, or fungicidal component in a high concentration, produces a residue in a very small amount at the end of service, excels in the ability to control the diffusion of the chemical component, and exhibits highly satisfactory transparency.
A further object of this invention is to provide a fish-luring composition which allows a fish-luring substance contained therein such as fish oil, animal oil, vegetable oil, or insect oil to be dissolved out in water at a constant rate for a long time, manifests a lasting fish-luring effect, and ensures a high efficiency of catch.
A further object of this invention is to provide an underwater antifouling composition which allows a chemical agent capable of retaining an antifouling effect without reference to such environmental conditions as water temperature and water current to be released at a constant speed for a long time and enables the antifouling effect to last for a long time.
A further object of this invention is to provide a solid fuel composition which produces stable combustion with a high calorific value for a long time, suffers spontaneous diffusion of the fuel component into the ambient air only sparingly even on exposure to elevated temperatures in the process of combustion or storage, and defies fluidization of the solid fuel and therefore enjoys safety.
A further object of this invention is to provide an oil-absorbent material which selectively and efficiently absorbs oil from the oil-water mixture or the sea surface having oil suspended in the form of a thin film thereon, retains the absorbed oil with high fastness, defies release (leakage) of the absorbed oil, enjoys high efficiency of oil recovery, and permits easy disposal as by incineration.
A further object of this invention is to provide an oil mist filter which absorbs oil mist efficiently, prevents the absorbed oil from trickling down or forming a ropy deposit on the surface, and offers effective use for a long time.
A further object of this invention is to provide an oil-absorbent pack which selectively and efficiently absorbs oil from the oil-water mixture or the sea surface having oil suspended in the form of a thin film thereon, excels in the ability to retain the absorbed oil, and allows easy storage and handling because of a very small volume to be assumed before absorption of oil.
A further object of this invention is to provide a sealing material for oil which, on contact with oil, quickly swells to bring about a high sealing effect on the oil, and retains such a high material strength as to escape loss of shape even after swelling with the absorbed oil.
A further object of this invention is to provide a highly printable paper which quickly absorbs selectively the solvent contained in an ink and consequently ensures effective reception of the ink, provides highly satisfactory fixation of the ink thereon even in the process of high-speed printing, and produces a print of beautiful finish free as from fogging.
A further object of this invention is to provide a thermosensitive recording material which prevents the molten substance in the thermosensitive coloring layer from adhering to and accumulating on the thermal head and inducing such adverse phenomena as formation of ropy deposit, impaired regularity of paper feeding, and missing dots and offers highly satisfactory resistance to oils and solvents such that, when the produced record is suffered to touch oil such as the grease of the human skin and the hair cream or solvent such as is contained in the adhesive tape or the adhesive agent, it is not obscured by yielding the colored part thereof to discoloration and the white part thereof to coloration.
A further object of this invention is to provide a pressure-sensitive recording sheet which produces, in response to the pressure exerted by a stylus, a recorded image suffering sparingly from blurring and enjoying a beautiful finish and offers highly satisfactory resistance to oils and solvents such that, when the recorded image is suffered to touch oil such as the grease of the human skin and the hair cream or solvent such as is contained in the adhesive tape or the adhesive agent, it is not blurred or vanished.
A further object of this invention is to provide a method for producing by a technically convenient procedure with high repeatability an oil-absorbent material which provides selective and efficient absorption of oil from the oil-water mixture or the sea surface having oil suspended in the form of a thin film thereon, retains the absorbed oil with high fastness, avoids spontaneous release (or leakage) of the absorbed oil and consequently enjoys highly satisfactory efficiency of oil recovery, and permits easy disposal as by incineration.
A further object of this invention is to provide a method for the removal of oil dissolved in water, which allows oil of meager or sparing solubility in water contained as dissolved in such water as the waste water or the polluted reservoir water to be selectively and quickly removed even when various impurities such as water-soluble substances and water-insoluble colloidal particles are present therein in addition to the oil.